This invention relates generally to the field of flow measurement of fluids, and more particularly to an improved means for sampling air flow in a large heating and/or cooling system, as measured by an electrical current flow proportional to average flow in the conduit. With some modification, the means may be also used for measuring liquid flow as well.
In known devices, usually referred to as anemometers, a measuring wire is heated and exposed to the flowing medium. A certain amount of cooling is experienced which can be related to the flow velocity of the medium. The cooling effect is evidenced by a change in electrical resistance of the wire.
In a large cross section conduit of flowing air, such a device can measure only the velocity at a particular point of measurement, and if the flow is turbulent or uneven in distribution, the measurement cannot be representative of the average flow in the conduit.